1. Field of the Invention
The present invention relates to a rotary filter for filtering or separating water out of water containing raw material such as fish guts and muds.
3. Description of the Related Art Statements
A rotary filter has been known and has been described in Japanese Utility Model Publication No. 55-9425. In the known rotary filter, a screen plate is shaped into a drum to form a screen drum and the screen drum is rotated. Water containing raw material is supplied into the screen drum from its one end and water-extracted raw material is taken out of the screen drum from its other end. By rotating the screen drum, the water is filtered out of the raw material due to the centrifugal force. Therefore, in order to increase the filtering efficiency, the screen drum has to be rotated at a higher speed.
In another known rotary filter, a screw having a spiral vane is fixedly arranged within the screen drum such that the screw is rotated together with the screen drum. In such a known rotary filter having the screen drum and the screw, the screen drum and the screw are rotated together with each other, and thus when the rotating speed is increased, the raw material is promptly discharged from the rotary filter while the water is not sufficiently filtered out. Therefore, in the known rotary filter, the water filtering efficiency could not be made high.